Forestación con Polylepis australis en suelos erosionados de las Sierras Grandes de Córdoba: evaluación del uso de terrazas y vegetación nodriza

the mountains of central argentina have serious soil erosion problems including the formation of erosion gullies. the forestation with native polylepis australis trees could be used to stop soil erosion and restore degraded areas. however their establishment in erosion gullies is hampered due to low soil fertility and water content. we evaluated whether p. australis establishment could be facilitated by the construction of stone terraces and the use of plants with potential nurse effects. we sowed and planted p. australis in a factorial design which included different degrees of protection by terraces and/or implanted vegetation types (lawns, poa stuckertii and control without vegetation) and in top layer and deep soils exposed by gully erosion (a1 and ii horizon). after 2/3 years, we evaluated survival and growth of planted p. australis, and establishment and growth of p. australis seedlings derived from the sowing. survival of the planted p. australis was 96% without differences between treatments. the effects of the protection treatment on growth were dependant on soil depth. in the top soils the use of terraces with p. stuckertii improved seedling growth, while in deeper soils only terraces with no vegetation improved growth. seedling establishment from the sowing experiment was very low (less than 1%) with no treatment effect, while their growth was best in terraces with p. stuckertii. growth of seedlings was 6 times slower than the growth of planted p. australis. we conclude that the best method to implant p. australis in gullies of the sierras grandes is planting and not seeding. we suggest the construction of terraces with p. stuckertii as a nurse plant in the top soils and the construction of terraces without vegetation in deep soils.